A pipette is known from the German Patent 28 51 532 having an elastic bulb or bellows. The draw of the bulb is restricted by given stops. In the known pipette, the liquid to be suctioned is first suctioned by means of a suction stroke into an intake top which is mounted on the casing of the pipette. Subsequently, the liquid is expelled out of the pipette by a discharge stroke. The known pipette is, for that reason, not suitable for the reception of micro-capillaries which themselves suction, i.e. in which the liquid to be suctioned is absorbed by a micro-capillary due to the capillary effect of liquids, without the need for generating, by means of a suction stroke, an internal pressure that is reduced in relation to the external pressure. If, in the known pipette, the position of the bulb, and thereby the volume inside the pipette were left unchanged during the reception of the liquid into a self-absorbing micro-capillary, the suctioning process would come to an end within a short period of time, inasmuch as the volume inside the pipette would be reduced by the fluid penetrating into the micro-capillaries and, consequently, a pressure would come into existence that prevents any further penetration of the liquid into the micro-capillaries. Also, if a discharge (pressure) stroke were carried out before the beginning of the suction process by the micro-capillaries, so as to carry out a suction stroke during the suction process, the operation of the known pipette would be too complicated. In addition, the bulb would have to be locked precisely in its position so as to prevent any tearing-off of the liquid thread in the micro-capillary.
Consequently, one object of the invention is the creation of a pipette of the type mentioned at the outset, which is suitable for the reception of a liquid, which can be used with self-absorbing micro-capillaries, and which is reliable and easy to operate and to maintain.